/**
 * The MIT License (MIT)
 *
 * Copyright (c) 2019 little-pan
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package org.walog;

import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

/** The write-ahead log.
 * 
 * @author little-pan
 * @since 2019-12-22
 *
 */
public interface Wal {

    int LSN_OFFSET_MASK = 0x3fffffff;

    Charset CHARSET = StandardCharsets.UTF_8;

    /** The lowest 30 bits of the lsn is offset in WAL file, and
     * the highest 34bits is the WAL file index.
     *
     * @return the WAL lsn
     */
    long getLsn();
    
    byte[] getData();

    long nextLsn() throws WalException;

    long nextFileLsn();

    Wal getLast();

}
